OBJECTIVE: The objective of this study was to compare the air leak duration of two regulated chest tube modes following pulmonary lobectomy. METHODS: This is a prospective randomized trial on 100 consecutive pulmonary lobectomies (2010-11) performed for lung cancer. A single 24-French chest tube was connected to an electronic system capable of maintaining the pleural pressure within preset values (regulated suction mode) or within a physiological range (regulated seal mode). Patients were randomized to two groups: Group 1, regulated individualized suction (range: -11 to -20 cmH(2)O, according to lobectomy type); Group 2, regulated seal (-2 cmH(2)O). The main endpoint was the duration of air leak (h) calculated from the end of the operation to a value consistently below 20 ml/min. Patients with prolonged air leak (>168 h) were connected to a portable device before discharge. Their air leak duration was considered as 192 h. The sample size was calculated to detect 1-day difference in air leak duration with a statistical power of 80%. RESULTS: The two groups were well matched for several baseline and surgical characteristics. No crossovers occurred between groups. The average air leak duration (Group 1: 28 vs Group 2: 22.2, P = 0.6), and the number of patients with prolonged air leak (Group 1: 5 vs Group 2: 4, P = 0.7) and with other complications (Group 1: 6 patients vs Group 2: 7 patients, P = 0.9) were similar between the groups. Sixteen patients of Group 1 and 21 of Group 2 had an air leak present immediately after extubation. Among them, patients of Group 2 (regulated seal) had an air leak lasting 34.5 h less than those of Group 1 (regulated suction) (52.9 vs 87.4, P = 0.07). CONCLUSIONS: Regulated seal is as effective and safe as regulated suction in managing chest tubes following lobectomy. This information demonstrates with objective data the non-superiority of regulated suction vs regulated seal and may assist in future investigations on regulated pleural pressure.